1. Technical Field
The present disclosure relates to thermoacoustic devices, and particularly to a method for making metal material based thermoacoustic device.
2. Description of Related Art
A thermophone based on the thermoacoustic effect was created by H. D. Arnold and I. B. Crandall (H. D. Arnold and I. B. Crandall, “The thermophone as a precision source of sound”, Phys. Rev. 10, pp 22-38 (1917)). The thermophone uses a platinum strip with a thickness of 7×10−5 cm as a thermoacoustic element. When signals are input into the platinum strip, heat is produced in the platinum strip according to the variations of the signal and/or signal intensity. Heat is propagated into the surrounding medium. The heat in the medium causes thermal expansion and contraction, and produces pressure waves in the surrounding medium, resulting in sound wave generation. The thermophone includes the platinum strip, clamps, and an electrical signal input device. The clamps are spaced apart from each other and are disposed on two ends of the platinum strip. The clamps are used for fixing the platinum strip. The middle region of the platinum strip is suspended while the two ends of the platinum strip are fixed. However, a suspending metal slice with thickness smaller than 7×10−5 centimeter (cm) is difficult to fabricate as a result of restriction of fabrication technology, thus, a smaller heat capacity per unit area of the metal slice cannot be achieved, which leads to sounds extremely weak because the heat capacity per unit area of the metal slice is too high.
What is needed, therefore, is to provide a method for making thermoacoustic device having a high acoustic intensity.